JP2005291818A - Penetration implement used for magnetic prospecting and magnetic prospecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a penetration implement used for magnetic prospecting and a magnetic prospecting method capable of performing magnetic prospecting without digging up probing holes, improving working efficiency, and specifying the pile length with high detection accuracy without being influenced by earth magnetism even in the case of a pile having a small quantity of reinforcing steel such as a cast-in-place pipe or in the case where a place separated from a foundation pile must be prospected by footing. <P>SOLUTION: This implement is constituted so that the foundation pile 3 is magnetized by a magnetic field generation device 8 mounted on a hollow part of an intrusion tip rod 1 or a slice rod 2, and that the intensity of the magnetic field at least in the prospecting shaft direction is measured by a three-dimensional magnetic sensor 6 mounted on the hollow part of the intrusion tip rod 1 or the slice rod 2. While pressing the intrusion tip rod 1 and the slice rod 2, the intensity of the magnetic field at different spots in the prospecting shaft direction, namely at each depth, is measured as prospected data. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a penetrating tool and a magnetic exploration method used for magnetic exploration, and more particularly to an penetrating tool and a magnetic exploration method used for magnetic exploration for detecting a tip position of a pile embedded in the ground such as a foundation pile.

  It is necessary to confirm the pile length of the foundation pile for the seismic assessment of the old structure in the year of enforcement or for the replacement of an aged structure. The pile length of the foundation pile must be investigated.

  Conventionally, in order to investigate the pile length of a foundation pile, a magnetic exploration method using a double coil type magnetic inclinometer has been performed. The magnetic exploration method specifies the pile length by measuring the residual magnetism of the foundation pile and the sensitive magnetism due to the earth's magnetic field. The exploration hole is excavated in the vicinity of the foundation pile to be measured by rotary boring, etc. The magnetic gradient, that is, the rate of change in the strength of the magnetic field is measured by inserting a double coil type magnetic inclinometer and moving at a constant speed, and the pile length is specified (for example, see Non-Patent Document 1).

  However, in the conventional magnetic exploration method, it is necessary to excavate an exploration hole of a predetermined depth by rotary boring or the like, and a large-scale machine is required and the exploration hole needs to be backfilled after magnetic exploration. There was a problem of becoming complicated. Further, when excavating a survey hole in a loose formation such as a sand layer, it is necessary to insert a non-magnetic guide tube as needed to prevent the collapse of the hole wall, resulting in a problem that work efficiency is lowered.

Furthermore, the conventional magnetic exploration method has a relatively large amount of steel materials such as H-shaped steel piles, and has a track record for objects with a large residual magnetic quantity, but the amount of rebar as in cast-in-place piles etc. When there is a small number of piles or when footing must be performed away from the foundation pile by footing, there is a problem that high detection accuracy cannot be expected due to the influence of geomagnetism.
“Shape Survey Method Manual for Bridge Foundations Using Magnetic Exploration” Ministry of Construction, Public Works Research Institute, March 1999

  The present invention has been made in view of such problems, and the object of the present invention is to perform magnetic exploration without excavating the exploration hole, improve work efficiency, Magnetics that can specify pile length with high detection accuracy without being affected by geomagnetism, even when piles with a small amount of reinforcing bars, such as piles, or when it is necessary to explore places away from the foundation pile by footing It is the point which provides the penetration tool and magnetic exploration method which are used for exploration.

In order to solve the above problems, the present invention has the following configuration.
The gist of the invention described in claim 1 is an penetration tool used for magnetic exploration in which the strength of a magnetic field in the vicinity of a measurement object including a steel material is measured and the tip position of the measurement object is detected in a non-contact manner. A penetration tip rod that is a cylindrical body that is formed of a nonmagnetic material and has a protruding tip portion, and a joint rod that is a cylindrical body composed of a nonmagnetic material that is added to the penetration tip rod; A magnetic sensor attached to the hollow portion of the penetrating tip rod or the joint rod and capable of measuring the strength of the magnetic field; and a magnetic field attached to the hollow portion of the penetrating tip rod or the joint rod and magnetizing the measurement object. A penetrating tool used for magnetic exploration, characterized by comprising a magnetic field generating means for generating a magnetic field.
According to a second aspect of the present invention, the magnetic field generating means is attached to the hollow portion of the penetrating tip rod or the connecting rod so as to generate a magnetic field in the direction of the search axis. It exists in the penetration tool used for the magnetic exploration of 1 description.
The gist of the invention described in claim 3 is a magnetic exploration method for performing magnetic exploration using the penetrating tool used in magnetic exploration according to claim 1 or 2, wherein the measurement is performed by the magnetic field generated by the magnetic field generating means. The present invention resides in a magnetic exploration method in which the strength of a magnetic field is measured by the magnetic sensor while an object is magnetized.
According to a fourth aspect of the present invention, there is provided a magnetic exploration method for performing magnetic exploration using the penetrating tool used for magnetic exploration according to claim 1 or 2, wherein the measurement is performed by the magnetic field generated by the magnetic field generating means. The present invention resides in a magnetic exploration method characterized in that after the object is once magnetized and the direction of the remanent magnetic pole of the measurement object is aligned, the magnetic field strength is measured by the magnetic sensor.

  The penetrating tool and the magnetic exploration method used in the magnetic exploration of the present invention magnetize the measurement object by the magnetic field generating means attached to the hollow portion of the penetrating tip rod or joint rod, and to the hollow portion of the penetrating tip rod or joint rod. By mounting at least the penetrating tip rod and the connecting rod, it is attached to the hollow portion of the penetrating tip rod or the connecting rod by configuring the magnetic sensor to measure at least the strength of the magnetic field in the exploration axis direction. Since the magnetic field strength can be measured by the magnetic sensor, magnetic exploration can be performed without drilling the exploration hole, the work efficiency can be improved, and the magnetic field from the measurement object can be magnetized. Measured with piles with a small amount of reinforcing bars, such as cast-in-place piles, and footing Even when it is necessary to explore at a distance from the object, the strength of the magnetic field from the measurement object can be measured without being affected by geomagnetism, and the pile length can be specified with high detection accuracy. There is an effect.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a penetrating tip rod of an embodiment of a penetrating tool used for magnetic exploration according to the present invention, (a) is a side view, and (b) is a longitudinal sectional view. . 2A and 2B are diagrams showing the configuration of the joint rod of the embodiment of the penetrating tool used for magnetic exploration according to the present invention, wherein FIG. 2A is a side view and FIG. 2B is a longitudinal sectional view. FIG. 3 is a diagram showing a configuration of the joint rod shown in FIG. 2 in which a magnetic field generator is attached to the hollow portion, and FIG. 4 shows a configuration of equipment used in the embodiment of the magnetic exploration method according to the present invention. FIG. 5 is a block diagram showing the configuration of the shape analysis apparatus shown in FIG. 4, and FIG. 6 is a diagram for explaining a horizontal magnetic field calculation method in the horizontal magnetic field calculation unit shown in FIG. FIG. 7 is a diagram for explaining the search results calculated by the search result calculation unit shown in FIG.
It is.

  In this embodiment, instead of excavating the exploration hole, the penetrating tool comprising the penetrating tip rod 1 shown in FIG. 1 and the joint rod 2 shown in FIGS. 2 and 3 is measured as shown in FIG. Magnetic exploration is performed by press-fitting in the vicinity of the foundation pile 3 which is an object. In addition to the piles (steel piles, cast-in-place piles), caisson (made of steel, reinforced concrete), wells (made of reinforced concrete), footings (made of reinforced concrete), steel sheet piles, buried pipes Steel pipes, reinforced concrete).

Referring to FIG. 1, the penetrating distal end rod 1 is a cylindrical body made of a nonmagnetic material such as stainless steel or aluminum alloy and having a projecting distal end portion. A female screw 4 for adding the joint rod 2 is formed. Moreover, the scale 5 is provided in the outer periphery at equal intervals in the axial direction. In addition, the tip angle of the penetrating tip rod 1 used in the present embodiment is 60 °, and the bottom area is about 10 cm ² .

  In the hollow portion of the penetrating tip rod 1, a three-dimensional magnetic sensor 6 capable of measuring the strength of magnetic fields in directions orthogonal to each other (x axis, y axis, z axis) is provided, and the z axis is the axial direction of the penetrating tip rod 1. (Hereinafter, the axial direction of the penetrating tip rod 1 is referred to as the exploration axis direction). The three-dimensional magnetic sensor 6 is composed of, for example, three Hall elements arranged in directions orthogonal to each other, and has a configuration capable of measuring the strength of magnetic fields in directions orthogonal to each other in a stationary state. Note that a fluxgate type sensor, a SQUID type sensor, or the like can be used instead of the Hall element.

  Referring to FIG. 2, the joint rod 2 is a cylindrical body made of a non-magnetic material such as stainless steel or aluminum alloy, and has a distal end portion behind the penetrating distal rod 1 and the upstream joint rod 2. A male screw 7 that is screwed with the end portion is formed, and a female screw 4 for adding the succeeding joint rod 2 is formed at the rear end portion. Moreover, the scale 5 is provided in the outer periphery at equal intervals in the axial direction.

  A plurality of joint rods 2 are prepared and used by adding them. However, as shown in FIG. 3, the foundation pile 3 is magnetized in a hollow portion in any one of the plurality of joint rods 2. A magnetic field generator 8 composed of a coil or the like is attached so that the direction of the generated magnetic field coincides with the axial direction of the penetrating tip rod 1. In this specification, the “direction of the magnetic field” indicates the direction of a line connecting the N pole and the S pole of a magnetic field generation source such as a magnet generating a magnetic field.

  In the magnetic exploration, as shown in FIG. 4, the joint rod 2 to which the magnetic field generator 8 is attached is connected to the penetrating tip rod 1, and the joint rod 2 is added vertically in the vicinity of the foundation pile 3 as a measurement object. Press fit. In addition, the existing press-fitting machine which penetrates a pipe (thin diameter steel pipe etc.) can be used for press-fitting of the penetration tip rod 1 and the joint rod 2. Further, the output cable from the three-dimensional magnetic sensor 6 provided on the penetrating tip rod 1 and the power supply line for supplying current to the magnetic field generator 8 provided on the joint rod 2 penetrate the joint rod 2 to be added. Since it is necessary, it can be cut off at one end with a connector or the like.

  The distance between the magnetic field generator 8 and the three-dimensional magnetic sensor 6 is such that when the magnetic field is measured by the three-dimensional magnetic sensor 6, the magnetic field from the magnetized foundation pile 3 is buried in the magnetic field generated by the magnetic field generator 8. The distance between the foundation pile 3 and the penetrating tip rod 1 (three-dimensional magnetic sensor 6) is set to be at least twice as large as possible. By simply connecting the joint rod 2 to which the magnetic field generating device 8 is attached to the penetrating tip rod 1, the distance between the magnetic field generating device 8 and the three-dimensional magnetic sensor 6 is equal to the foundation pile 3 and the penetrating tip rod 1 (three-dimensional magnetic sensor). 6), the joint rod 2 to which the magnetic field generator 8 is not attached is inserted between the penetrating tip rod 1 and the joint rod 2 to which the magnetic field generator 8 is attached. Should be connected.

  The intensity of the magnetic field generated by the magnetic field generator 8 is set to such an extent that the influence of geomagnetism can be ignored when the magnetic field is measured by the three-dimensional magnetic sensor 6. That is, the strength of geomagnetism near Japan is about 50,000 (nT), and the strength of the magnetic field measured by the three-dimensional magnetic sensor 6 is 0.2 (mT) = 200,000 (nT) or more. In this way, the strength of the magnetic field generated by the magnetic field generator 8 is set to reduce the influence of geomagnetism.

  As shown in FIG. 4, the magnetic field generator 8 is supplied with a current from the power supply device 9 through the power supply line, and a DC current is supplied as a power source supplied from the power supply device 9 to the magnetic field generator 8. A direct current power supply and an alternating current power supply for supplying an alternating current can be used. When a DC power supply is used as the power supply device 9, a constant DC current is supplied to the magnetic field generator 8 to generate a magnetic field with a constant strength, and the penetration tip rod 1 and the joint rod 2 are press-fitted. Accordingly, the magnetic field generator 8 is moved in the search axis direction. In addition, when an AC power supply is used as the power supply device 9, the strength of the magnetic field generated by the magnetic field generation device 8 periodically varies and the direction of the magnetic field is periodically reversed. Therefore, a desired magnetic field can be measured by signal processing the measurement result.

  A scale detection sensor 10 for detecting a scale 5 provided on the outer circumference of the penetrating tip rod 1 and the joint rod 2 is installed, and the scale by the scale detection sensor 10 is parallel to the press-fitting of the penetrating tip rod 1 and the joint rod 2. The magnetic field strengths in the x-axis direction, y-axis direction, and z-axis direction are respectively measured at the detection timing. That is, the output from the three-dimensional magnetic sensor 6 is amplified by the amplifier 11 and input to the data collector 12 at the scale detection timing by the scale detection sensor 10. Therefore, the data collector 12 collects the strength of the magnetic field in the x-axis direction, the y-axis direction, and the z-axis direction for each depth (scale 5) as exploration data.

  The exploration data collected by the data collector 12 is analyzed by the shape analysis device 13. The shape analysis device 13 refers to FIG. 5, and the exploration data input unit 14 to which the exploration data from the data collector 12 is input, , A horizontal magnetic field calculation unit 15, an exploration result calculation unit 16, and a data output unit 17.

The survey data input unit 14, and strength B _X in the x-axis direction of the magnetic field from the data collector 12 each depth as the survey data, and strength B _Y of the magnetic field in the y-axis direction, the z-axis direction of the magnetic field Strength _BZ is input.

The horizontal magnetic field calculation unit 15 calculates the magnetic field strength B _H of the horizontal component according to Equation 1 shown below. That is, as shown in FIG. 6, three-dimensional even x-axis and y-axis magnetic sensor 6 rotates and changes, and strength B _X of the magnetic field in the x-axis direction, the strength of the magnetic field in the y-axis direction B _An accurate horizontal component magnetic field strength B _H is calculated from _Y.

The exploration result calculation unit 16 calculates tan θ = B _H / B _Z from the magnetic field strength B _H of the horizontal component and the magnetic field strength B _{Z in} the vertical direction (z-axis direction).
In this way, tan θ = B _H / B _Z for each depth is calculated and output to the data output unit 17 such as a printer as a graph or a table.

When the magnetized foundation pile 3 is regarded as a magnet, magnetic field lines as shown in FIG. 7 are generated from the foundation pile 3, and tan θ = B _H / B _Z is calculated to calculate the horizontal component magnetic field. Since the change in the angle of the magnetic field lines can be detected by grasping it as the ratio between the strength B _H and the magnetic field strength B _Z in the vertical direction, the graph or table output from the data output unit 17 shows the A clear fluctuation centering on the tip position can be confirmed, and the pile length of the foundation pile 3 can be detected.

  In the present embodiment, the magnetic field strength in the x-axis direction, the y-axis direction, and the z-axis direction is measured by the three-dimensional magnetic sensor 6, but only the magnetic field strength in the z-axis direction is measured. A magnetic sensor may be used. Since the influence of geomagnetism is weakened by the magnetic field generated by the magnetic field generator 8, the depth at which the magnetic field strength Bz in the z-axis direction becomes zero, that is, in the direction of the search axis from the magnetized foundation pile 3 is obtained. It is possible to detect the pile length of the foundation pile 3 based on the depth at which the magnetic field is reversed.

Furthermore, in the present embodiment, taking into account the rotation of the three-dimensional magnetic sensor 6, the horizontal component magnetic field strength B _H , the x-axis magnetic field strength _BX, and the y-axis magnetic field strength are used. By calculating from _BY , if positioning is performed so that the three-dimensional magnetic sensor 6 does not rotate during the movement of the z-axis (vertical direction), that is, the x-axis and the y-axis do not move, the magnetic field of the horizontal component In the exploration result calculation unit 16 without calculating the intensity B _H of tan θ = B _X / B _Z using the magnetic field intensity B _X in the x-axis direction or the magnetic field intensity B _Y in the y-axis direction, tan θ = B _Y / B _Z may be calculated. In this case, instead of the three-dimensional magnetic sensor 6, the magnetic field strengths in directions orthogonal to each other (x axis, y axis, z axis) are measured. Possible two-dimensional magnetic sensors can be used.

Next, another embodiment of the present invention will be described in detail with reference to FIG.
FIG. 8 is a longitudinal sectional view showing the configuration of another embodiment of the penetrating tool used for magnetic exploration according to the present invention.

  In FIG. 8A, a three-dimensional magnetic sensor 6 and a magnetic field generator 8 are attached to the hollow portion of the penetrating tip rod 1. Thus, when the distance between the magnetic field generator 8 and the three-dimensional magnetic sensor 6 can be set to at least twice the distance between the foundation pile 3 and the three-dimensional magnetic sensor 6, the same rod (penetrating tip rod) The three-dimensional magnetic sensor 6 and the magnetic field generator 8 may be attached to the 1 or the joint rod 2).

  8B, a magnetic field generator 8 is attached to the hollow portion of the penetrating tip rod 1, and the three-dimensional magnetic sensor 6 is mounted on the hollow portion of the joint rod 2 as shown in FIG. 8C. You may make it attach. In other words, the upper and lower positions of the magnetic field generator 8 and the three-dimensional magnetic sensor 6 may be in the upper position.

  As described above, according to the present embodiment, the foundation pile 3 is magnetized by the magnetic field generator 8 attached to the hollow portion of the penetrating tip rod 1 or the joint rod 1, and the penetrating tip rod 1 or the joint rod 2. The penetration tip rod 1 can be obtained by simply press-fitting the penetration tip rod 1 and the joint rod 2 by measuring at least the strength of the magnetic field in the direction of the search axis by means of a three-dimensional magnetic sensor 6 attached to the hollow portion. Alternatively, since the strength of the magnetic field can be measured by the three-dimensional magnetic sensor 6 attached to the hollow portion of the joint rod 2, magnetic exploration can be performed without excavating the exploration hole, and work efficiency can be improved. Since the foundation pile 3 can be magnetized and the magnetic field from the foundation pile 3 can be strengthened, a pile with a small amount of reinforcing bars, such as a cast-in-place pile, etc. Even when it is necessary to explore away from the foundation pile 3 due to the ring, the strength of the magnetic field from the foundation pile 3 can be measured without being affected by geomagnetism, and the pile length is specified with high detection accuracy. There is an effect that can be.

  In the present embodiment, the depth is detected by the scale 5 provided on the outer circumferences of the penetrating tip rod 1 and the joint rod 2. However, the winding displacement meter (the length of the joint rod 2 is the same as the length of the joint rod 2). In the case of 1 m, a displacement meter for measuring 1 m) may be installed on the press-in (press-fit) machine body, and the depth may be detected by electrically detecting the push-in (press-in) amount of the rod. . In this case, the scale of the displacement meter is also changed every time in the process of adding the connecting rod 2.

  In this embodiment, the magnetic field is measured in a state where the foundation pile 3 is magnetized by the magnetic field generator 8. However, after the foundation pile 3 is once magnetized by the magnetic field generator 8, the magnetic field generator is used. The generation of the magnetic field by 8 may be stopped and the magnetic field may be measured. Also in this case, since the directions of the magnetic poles of the residual magnetism of the foundation pile 3 are aligned once by magnetizing, the magnetic field due to the residual magnetism becomes strong and can be detected with high accuracy.

  Note that the present invention is not limited to the above-described embodiments, and it is obvious that the embodiments can be appropriately changed within the scope of the technical idea of the present invention. In addition, the number, position, shape, and the like of the constituent members are not limited to the above-described embodiment, and can be set to a suitable number, position, shape, and the like in practicing the present invention. In each figure, the same numerals are given to the same component.

It is a figure which shows the structure of the penetration tip rod of embodiment of the penetration tool used for the magnetic exploration which concerns on this invention, (a) is a side view, (b) is a longitudinal cross-sectional view. It is a figure which shows the structure of the joint rod of embodiment of the penetration tool used for the magnetic exploration which concerns on this invention, (a) is a side view, (b) is a longitudinal cross-sectional view. It is a figure which shows the structure of the joint rod shown in FIG. 2 with which the magnetic field generator is attached to the hollow part. It is a figure which shows the apparatus structure used with embodiment of the magnetic exploration method which concerns on this invention. It is a block diagram which shows the structure of the shape analysis apparatus shown in FIG. It is a figure for demonstrating the calculation method of the horizontal magnetic field in the horizontal magnetic field calculation part shown in FIG. It is a figure for demonstrating the search result calculated in the search result calculation part shown in FIG. It is a longitudinal cross-sectional view which shows the structure of other embodiment of the penetration tool used for the magnetic exploration which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Penetration tip rod 2 Joint rod 3 Foundation pile 4 Female screw 5 Scale 6 Three-dimensional magnetic sensor 7 Male screw 8 Magnetic field generator 9 Power supply device 10 Scale detection sensor 11 Amplifier 12 Data collector 13 Shape analysis device 14 Search data input part 15 Horizontal magnetic field calculation unit 16 Search result calculation unit 17 Data output unit

Claims (4)

An intruder used for magnetic exploration that measures the strength of a magnetic field in the vicinity of a measurement object including a steel material and detects the tip position of the measurement object in a non-contact manner,
A penetrating tip rod that is a cylindrical body formed of a non-magnetic material and having a protruding tip portion formed thereon;
A joint rod that is a cylindrical body composed of a non-magnetic material joined to the penetrating tip rod;
A magnetic sensor attached to the hollow portion of the penetrating tip rod or the joint rod and capable of measuring the strength of the magnetic field;
A penetrating tool used for magnetic exploration, comprising: a magnetic field generating means for generating a magnetic field for magnetizing the measurement object, attached to a hollow portion of the penetrating tip rod or the joint rod.   2. The penetrating tool used for magnetic exploration according to claim 1, wherein the magnetic field generating means is attached to a hollow portion of the penetrating tip rod or the joint rod so as to generate a magnetic field in the direction of the exploration axis. A magnetic exploration method for performing magnetic exploration using the penetrating tool used for magnetic exploration according to claim 1 or 2,
A magnetic exploration method characterized by measuring the strength of a magnetic field by the magnetic sensor in a state where the measurement object is magnetized by a magnetic field generated by the magnetic field generation means. A magnetic exploration method for performing magnetic exploration using the penetrating tool used for magnetic exploration according to claim 1 or 2,
The magnetic field is measured by the magnetic sensor after the measurement object is once magnetized by the magnetic field generated by the magnetic field generation means and the direction of the remanent magnetic pole of the measurement object is aligned. Magnetic exploration method.

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